Georef: fix angle computation
Georef: fix angle computation

we did not check if a == c in the angle computation thus giving wrong
directions.

fix http://jira.canaltp.fr/browse/NAVITIAII-1044

datanel/navitia,kinnou02/navitia,xlqian/navitia,francois-vincent/navitia,kadhikari/navitia,djludo/navitia,prhod/navitia,CanalTP/navitia,is06/navitia,fueghan/navitia,stifoon/navitia,frodrigo/navitia,is06/navitia,VincentCATILLON/navitia,francois-vincent/navitia,is06/navitia,Tisseo/navitia,lrocheWB/navitia,thiphariel/navitia,kadhikari/navitia,thiphariel/navitia,lrocheWB/navitia,ballouche/navitia,CanalTP/navitia,kadhikari/navitia,frodrigo/navitia,ballouche/navitia,Tisseo/navitia,xlqian/navitia,ballouche/navitia,pbougue/navitia,prhod/navitia,xlqian/navitia,djludo/navitia,prhod/navitia,antoine-de/navitia,antoine-de/navitia,patochectp/navitia,thiphariel/navitia,datanel/navitia,kinnou02/navitia,patochectp/navitia,datanel/navitia,CanalTP/navitia,francois-vincent/navitia,Tisseo/navitia,antoine-de/navitia,CanalTP/navitia,VincentCATILLON/navitia,patochectp/navitia,frodrigo/navitia,kinnou02/navitia,stifoon/navitia,TeXitoi/navitia,antoine-de/navitia,TeXitoi/navitia,pbougue/navitia,pbougue/navitia,is06/navitia,ballouche/navitia,thiphariel/navitia,VincentCATILLON/navitia,fueghan/navitia,patochectp/navitia,VincentCATILLON/navitia,lrocheWB/navitia,Tisseo/navitia,datanel/navitia,fueghan/navitia,kinnou02/navitia,djludo/navitia,xlqian/navitia,stifoon/navitia,frodrigo/navitia,francois-vincent/navitia,prhod/navitia,xlqian/navitia,Tisseo/navitia,pbougue/navitia,lrocheWB/navitia,stifoon/navitia,TeXitoi/navitia,CanalTP/navitia,kadhikari/navitia,fueghan/navitia,TeXitoi/navitia,djludo/navitia